Field of the Invention
The invention relates to a pressure sensor device that is suitable, in particular, for detecting high pressures. Pressure sensor devices of this type are used, in particular, for detecting fuel pressure in a fuel supply unit of a motor vehicle.
A known pressure sensor device (see Published, Non-Prosecuted German Patent Application DE 198 33 712 A1) has a diaphragm body with a cylindrical recess in which the working medium is situated. A diaphragm is formed in the diaphragm body in a manner adjoining the recess. On the diaphragm, a sensor chip is disposed concentrically with respect to the cylindrical recess. On the sensor chip, sensor elements are disposed centrosymmetrically with respect to the central point of the sensor chip and thus the axis of the cylindrical recess. The sensor elements are connected up in the form of a Wheatstone bridge and yield a sensor signal that represents the pressure in the working medium. A good measurement behavior of the sensor elements in the known pressure sensor device is ensured only when the sensor elements lie approximately in the region of the end facexe2x80x94projected on the sensor chipxe2x80x94of the cylindrical recess. The consequence of this, however, is that the sensor chip must in each case be adapted to the diameter of the cylindrical recess. In the case of relatively large diameters of the recess, this also inevitably necessitates a relatively large sensor chip, which increases the costs for the production thereof.
It is accordingly an object of the invention to provide a pressure sensor device which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is produced cost-effectively and at the same time has a high sensitivity in detecting pressure.
With the foregoing and other objects in view there is provided, in accordance with the invention, a pressure sensor device. The pressure sensor device contains a diaphragm having a first side acted upon by a working medium, a second side, and a central point. A sensor chip is disposed on the second side of the diaphragm remote from the working medium. The sensor chip has a measuring bridge with four sensor elements, the sensor elements are formed in two pairs with the sensor elements within the pairs disposed parallel to one another and the pairs are disposed at right angles to one another. The sensor elements are disposed such that the sensor elements are closely spaced apart from one another in an edge region of the sensor chip that faces toward the central point of the diaphragm.
In accordance with an added feature of the invention, the sensor elements are piezoresistive sensor elements.
In accordance with a further feature of the invention, the sensor chip has a further measuring bridge. The sensor chip is disposed on the diaphragm in such a way that both the measuring bridge and the further measuring bridge are acted upon by equivalent mechanical stresses.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a pressure sensor device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.